my current configuration is (Differential - Cascade - Common Emitter (emitter Resistance) - Common Emitter (Emitter Resistance)) i got Av=4 k v/v and input and output impendace as desired but am having triuble with Flow and Fhigh :S
thanx for the link..i hecked it out but i need to build it not using op-amps but BJTs...
i only have problem with Flow now..i need it less than 200Hz...when i add couplin capcitor to the input signal i loose my gain :S!
Changing Flow is simply a matter of changing capacitor values. Achieving high bandwidth (Fhigh) and high gain is much more challenging. You can get more bandwidth by:
1. Using more lower gain cascaded stages.
2. Increasing power dissipation. This works because unwanted capacitance (Ccb, etc.) is relatively constant as a function of collector current, but resistor values go down, improving the high-frequency response.
3. Using cascode stages to minimize the Miller effect.